Murderers and other violent criminals were among the 505 prisoners who have been let out of prison early in error over the past decade — equivalent to just under one every week.

Between 2014 and 2015, 48 convicts and suspects were freed from prison or custody by mistake, according to the figures, which were released following a freedom of information request. Two of those released by mistake that year have not been returned to custody — including an alleged sex offender who was released early from court.

The stats show the blunders appear to have peaked in 2009 to 2010, when 68 prisoners were released in error.

A Prison Service spokesman told Press Association: “Public protection is our top priority. These incidents are very rare, but we are not complacent. The number of releases in error has fallen by almost a third since 2009 and the vast majority are returned to custody very quickly. The Prison Service investigates each incident and they are reported to the police for further action.”

However, Conservative MP Philip Davies, who sits on the Commons justice committee, told the Press Association the figures were “disturbing.” Shadow justice minister Andy Slaughter said the public was likely to be “stunned” by the report, adding that the figures showed “a further sign of crisis” in England and Wales’ prisons.

Murderers released early

Blunders have included:

Martynas Kupstys was on remand for murder in high-security prison HMP Lincoln, charged with killing a man who was found dead following a house fire in January 2014. In August, Kupstys was let out early — despite his pleas to prison guards that he was supposed to be headed for court in a prison van — and waited for three hours at a nearby bus stop before officers realised their mistake and he was located and returned to prison. Kupstys was later convicted of murder and jailed.

In July last year, a prisoner from HMP Hewell was released early after there was a reported mix-up with an inmate with the same surname. He was returned to prison one day later.

In 2012, The Daily Telegraph reported that four prisoners had been wrongly released from high security Strangeways prison. An arsonist and a violent criminal were among those released in error.